<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>root伪类器</title>
	</head>
	<style>
		:root{
			background: green;
		}
		body{
			background: yellow;
		}
	</style>
	<body>
		<h1>ROOT伪类选择器</h1>
		<p>root既是根元素，例如整个页面的root元素就是html。</p>
	</body>
</html>
